International Journal of Plant & Soil Science

Soil fertility decline caused by continuous cultivation is a major constraint to sustainable maize production in tropical regions. Integrated nutrient management, which combines organic sources such as poultry manure and Gliricidia sepium with inorganic NPK fertiliser, can improve soil nutrient status, enhance soil properties and increase crop yield more effectively than sole applications. A field experiment was conducted to evaluate the effects of combined poultry manure, Gliricidia sepium and NPK 15:15:15 on soil nutrient status and maize yield in a 3 by 2 factorial experiment involving 5 t ha⁻¹ poultry manure, 5 t ha⁻¹ Gliricidia sepium leaves and 150 kg ha⁻¹ NPK 15:15:15 arranged in a randomised complete block design. The treatment combinations were replicated three times. Data were collected on maize growth, grain-yield parameters and soil chemical characteristics, and were subjected to analysis of variance using SPSS Version 16.0. The results showed that growth, yield and soil nutrient content were significantly (P < 0.05) influenced by the treatments. The highest growth parameters were obtained with the combined application of poultry manure and Gliricidia sepium, while the combined use of NPK 15:15:15, Gliricidia sepium and poultry manure produced the highest maize grain-yield parameters. The combined use of poultry manure with Gliricidia sepium significantly improved soil nutrient status. Sole NPK 15:15:15 application reduced soil pH compared with the combined use of poultry manure, Gliricidia sepium and NPK 15:15:15. Organic wastes should therefore be integrated with inorganic fertiliser to enhance soil nutrient status and crop yield in the study area.